Friday, 29 August 2014

Exploring the seaweeds of Europe’s largest artificial reef (Frithjof 29/08/2014)

Three diving marine
scientists from the Hellenic Centre for Marine Research (HCMR) came to Scotland
for a 10-day trip in order to explore the hitherto-unknown seaweed communities
of the Loch Linnhe Artificial Reef in western Scotland (July 19-29). The
project was hosted by the UK National
Facility for Scientific Diving (NFSD), headed by Dr. Martin Sayer. Maria
Salomidi, Kostas Tsiamis and Vasilis Gerakaris flew to Aberdeen, where they
visited Frithjof at Oceanlab and in his home overlooking the Ythan Estuary.
After one night there, they hit the long road from Aberdeen to the scenic West
Highlands.

The Loch Linnhe
Artificial Reef was built between 1998-2006, led by Martin Sayer and Tom
Wilding at the Scottish Association for Marine Science, in cooperation with
Foster Yeoman Ltd, operators of the Glensanda quarry in Morvern (http://www.sams.ac.uk/tom-wilding/overview-artificial-reef
). This large “superquarry” produces agglomeration for worldwide exports. This
operation produces a fine powder as byproduct, which has no commercial value.
In the late 1990s, this led to the idea of using it in a mixture with concrete
for producing a type of breeze block-like elements which would be deployed in
piles (termed “modules”) on the seabed of Loch Linnhe east of the Isle of
Lismore. The rationale was that this would enhance structural diversity in a low-diversity
soft-sediment area, resulting in locally increased biodiversity, standing stock
of biota – in particular also of species of commercial interest. Even though
the animal biodiversity and ecology, hydrology, biogeochemistry and other
aspects of the reef had formed the centre of interest so far, no studies at all
had considered the seaweeds of the reef.

The team managed to
conduct a total of 25 diving operations, exploring the seaweed communities of
the artificial reef from around 27 to 10 m depth and at natural reefs from 18 m
to the surface. The wreck of the Breda, sunk in WW II by German bombers, was
also surveyed – de facto it is an artificial reef which has been in the sea for
over 70 years. The team was incredibly lucky with the weather: During the week
of diving, the sea was flat calm and the sky mostly cloudless. Temperatures
reached a record high ever recorded for Oban.

A total of around 50
seaweed species were recorded. It was also observed that on all except the
modules > 20 m deep, seaweed standing stock exceeded animal standing stock
by a large margin. Seaweed specimens were conserved on herbarium sheets; the
communities on the reef were also amply documented by quadrat photographs.

We would like to thank
Martin Sayer, Andy Mogg, Elaine Azzopardi and Hugh Brown at NFSD and the crew
of the RV Seol Mara for their excellent support to the project which involved
rather complex logistics and long working hours for everyone. Special thanks go
to Martin and Jane Sayer for their legendary hospitality. The team would also like
to acknowledge the EU program ASSEMBLE
for funding this project.